1. Field of the Invention
The present invention relates to the selective catalytic cracking of mixtures of isopropylphenol isomers in order to reduce the content of the para-isopropylphenol isomer therein and to thereby provide an isopropylphenolic product enriched in the meta-isopropylphenol isomer.
2. Description of the Prior Art
Propylated phenolic products such as meta-isopropylphenol and mixtures containing it are useful materials in the synthesis of various products such as adhesives, agricultural chemicals and pharmaceuticals. It is known to prepare such products via the alkylation of phenolic compounds with such propylating agents as propylene and isopropanol, and a variety of alkylation catalysts are known to promote such a reaction. For example, U.S. Pat. Nos. 3,959,394; 3,439,048; 3,426,358; 3,426,082; 3,409,678; 3,382,283; 3,367,981; 3,265,742; 3,185,737; 3,133,974; 3,082,258 and 3,071,595, all disclose alkylation of phenols over a variety of catalyst such as Friedel Crafts catalysts (AlCl.sub.3, HF, BF.sub.3, etc.), zinc halides, alumina, aluminum phenoxide, alkane sulfonic acids and the like. Although many of these reactions are said to favor formation of the ortho-alkylphenols, reaction products in all instances contain at least some of the para- and meta-isomers as well.
Separation of the desired meta-isomer of propylated phenolic compounds from mixtures which also contain the para isomer of isopropylphenol is difficult to accomplish using conventional fractionation techniques since the boiling points of these two isomers are so close. There is thus a need to identify phenolic compound synthesis process procedures, conditions and catalysts which can be used to selectively prepare mixtures containing maximized amounts of desirable meta-isopropylphenolic compounds. Accordingly, it is an object of the present invention to provide a process for producing a product mixture comprising increased concentrations of the meta-isomer of isopropylated phenol.